U.S. patent application number 11/410800 was filed with the patent office on 2006-10-26 for optical lens, light emitting device package using the optical lens, and backlight unit.
Invention is credited to Jun Ho Jang, Jung Hoon Seo.
Application Number | 20060238884 11/410800 |
Document ID | / |
Family ID | 36764640 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060238884 |
Kind Code |
A1 |
Jang; Jun Ho ; et
al. |
October 26, 2006 |
Optical lens, light emitting device package using the optical lens,
and backlight unit
Abstract
An optical lens, a light emitting device package using the
optical lens and a backlight unit are disclosed, whereby light
irradiated upward of a light emitting device is refracted from a
bottom refraction surface to allow reaching a reflection surface,
and an optical lens is mounted for reflecting the light sideways of
the lens from the reflection surface to minimize an amount of light
irradiated upward of the lens while increasing the amount of light
irradiated toward the lateral surface of the lens, thereby limiting
the generation of a hot spot to the maximum. The present invention
dispenses with a hot spot baffle plate and a complicated assembly
process to enable to reduce the number of parts and to decrease the
thickness of a panel.
Inventors: |
Jang; Jun Ho; (Anyang-si,
KR) ; Seo; Jung Hoon; (Seoul, KR) |
Correspondence
Address: |
MCKENNA LONG & ALDRIDGE LLP
1900 K STREET, NW
WASHINGTON
DC
20006
US
|
Family ID: |
36764640 |
Appl. No.: |
11/410800 |
Filed: |
April 26, 2006 |
Current U.S.
Class: |
359/653 ;
257/E33.073 |
Current CPC
Class: |
F21V 5/04 20130101; G02F
1/133605 20130101; F21Y 2115/10 20160801; F21V 7/0091 20130101;
G02B 19/0066 20130101; G02F 1/133603 20130101; G02B 19/0061
20130101; G02B 19/0071 20130101; G02B 19/0028 20130101 |
Class at
Publication: |
359/653 |
International
Class: |
G02B 3/00 20060101
G02B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2005 |
KR |
10-2005-0034473 |
Apr 26, 2005 |
KR |
10-2005-0034543 |
Claims
1. An optical lens comprising: a reflection surface formed thereon
for reflecting light emitted upwards from a bottom thereof; and a
bottom refraction surface for refracting the light emitted upwards
from the bottom thereof to allow reaching the reflection
surface.
2. The lens as defined in claim 1, wherein the reflection surface
is inclined, and the bottom refraction surface is symmetrically
inclined from the reflection surfaces with respect to a horizontal
line.
3. The lens as defined in claim 1 further comprising an external
refraction surface laterally formed for refracting the light
reflected from the reflection surface and the light irradiated
toward a bottom lateral surface thereof to allow laterally being
emitted.
4. The lens as defined in claim 3, wherein a body of the optical
lens including the reflection surface, the bottom refraction
surface and the external refraction surface is shaped of a
hemisphere.
5. The lens as defined in claim 1, wherein the reflection surface
is coated with a reflective film.
6. A light emitting device package comprising: a light emitting
device for emitting light; and an optical lens disposed with a
reflection surface formed thereon for reflecting light emitted
upwards from the light emitting device and a bottom refraction
surface for refracting the light emitted upwards from the light
emitting device and allowing the light to reach the reflection
surface.
7. The package as defined in claim 6 further comprising: a base
member on which the light emitting devices are bonded; terminals
electrically connected to the light emitting devices; and a molding
unit for partially exposing the terminals and encompassing the
light emitting devices and the base member, wherein the optical
lens is attached to an upper surface of the molding unit.
8. The package as defined in claim 7, wherein the base member is a
hit slug or a sub-mount substrate.
9. The package as defined in claim 7, wherein the light emitting
device is made of one of a group consisting of: devices including a
blue light emitting device for emitting blue light and a yellow
light emitting device for emitting yellow light: devices including
a red light emitting device for emitting red light, a green light
emitting device for emitting green light and a blue light emitting
device for emitting blue light; and a single light emitting device
for emitting white light.
10. The package as defined in claim 6 further comprising an
external refraction surface formed at a lateral surface of the
optical lens for refracting light reflected from the reflection
surface and light irradiated to the lateral surface of the light
emitting device to be irradiated to the lateral surface of the
optical lens.
11. The package as defined in claim 10, wherein the body of the
optical lens composed of the reflection surface, the bottom
refraction surface and the external refraction surface is shaped of
a hemisphere.
12. The package as defined in claim 6, wherein the reflection
surface is inclined, and the bottom refraction surface has an
inclination symmetrically inclined from the reflection surface.
13. The package as defined in 12, wherein the bottom reflection
surface further comprises a marginal refraction surface
symmetrically inclined from the bottom refraction surface relative
to a perpendicular line for refracting light in such a manner that
light emitted from an upper margin of the light emitting device can
have a path on which the light is reflected from the reflection
surface.
14. The package as defined in claim 6, wherein the bottom
refraction surface is concaved.
15. The package as defined in claim 6, wherein the reflection
surface is coated with a reflective film.
16. The package as defined in claim 15, wherein the reflective film
is further coated thereon with non-permeable material film.
17. A backlight unit comprising: a substrate; a plurality of light
emitting devices packaged in the substrate for emitting light; a
plurality of optical lenses disposed with a reflection surface
formed thereon for reflecting light emitted upwards from the
plurality of light emitting devices and a bottom refraction surface
for refracting the light emitted upwards from the plurality of
light emitting devices and allowing the light to reach the
reflection surface; and a diffusion plate disposed on the plurality
of optical lenses.
18. The backlight unit as defined in claim 17, wherein the
diffusion plate is disposed thereon with a liquid crystal display
panel.
19. The backlight unit as defined in claim 17 further comprising an
external refraction surface formed at a lateral surface of the
optical lens for refracting light reflected from the reflection
surface and light irradiated to the lateral surface of the light
emitting device to be irradiated to the lateral surface of the
optical lens.
20. The backlight unit as defined in claim 19, wherein the body of
the optical lens composed of the reflection surface, the bottom
refraction surface and the external refraction surface is shaped of
a hemisphere.
Description
[0001] This application claims the benefit of the Korean
Application No. 10-2005-0034473 filed on Apr. 26, 2005 and
10-2005-0034543 filed on Apr. 26, 2005 which are hereby
incorporated by reference.
BACKGROUND
[0002] This description relates to an optical lens, a light
emitting device package using the optical lens and a backlight
unit.
[0003] A conventional light emitting diode is optically disposed
with a domed lens, and light is limitedly distributed to within a
predetermined region relative to a central axis. If a liquid
crystal display (LCD) backlight unit is manufactured using the
light emitting diode, one potential problem is that an even light
characteristic cannot be obtained due to light emitting
characteristic of the light emitting diode.
[0004] It implies that a considerable distance is needed to evenly
combine white light radiated from the light emitting diode, making
it difficult to obtain a uniform light characteristic from a thin
backlight unit. In other words, a backlight unit using a light
emitting diode brings about a disadvantage of increasing the
thickness of an LCD system.
[0005] FIG. 1 illustrates a light path from a lens for lateral
light emitting according to the prior art, where a light emitting
diode (LED.10) is disposed on a domed lens 20. The domed lens 20 is
formed thereon with an inclined conical groove 21 and its side is
formed with a V-shaped groove 22.
[0006] If light emitted from the LED 10 contacts a surface of the
conical groove 21, the light is reflected from the inclined conical
groove 21 to be radiated sidewise of the lens. If light contacts
the V-shaped groove 22 of the lens 20, the light passes through the
lens 20 to be radiated sideways of the lens.
[0007] In other words, an LED for laterally emitting (or
side-emitting) light (hereinafter referred to as a lateral LED)
according to the prior art serves to laterally radiate light
emitted from the LED 10 using a lens.
[0008] Meanwhile, the injection-molded lens 20 is formed at a
region corresponding to an apex 22a of the V-shaped groove 22 with
prominences and depressions (unevenness) if closely looked at (for
example, in less than a millimeter unit), such that light of the
LED 10 emitted from the region is not radiated sideways of the lens
10 but upwards of the lens 10.
[0009] FIG. 2 is a schematic perspective view of an LED package of
FIG. 1, where the LED is bonded to a slug, and the slug is disposed
at sides thereof with leads 31 and 32 which are in turn
electrically bonded to the LED.
[0010] Furthermore, the LED and the slug are molded by molding
means in order to expose a light emitting surface of the LED and
the leads 31 and 32, and the lens 20 of FIG. 1 encompassing the LED
is bonded to the molding means.
[0011] FIG. 3 is a light emitting distribution table of an LED
package according to the prior art, where it shows that a large
amount of light is radiated sidewise of the package as indicated in
`a` and `b` of the distribution table while a small amount of light
is radiated through a center of the package.
[0012] FIG. 1 implies that although most of the light is radiated
sideways of the lens, some of the light is radiated upwards of the
lens. In other words, the LED package thus described cannot
implement a perfect light emission to lateral surfaces, such that
if it is used as a light source for a display, light is partially
emitted from the light emitting diode relative to the center of the
LED package, resulting in a problem in making a planar light
source.
[0013] To be more specific, the partial emission of light relative
to the center of the LED package results in so-called light
irregularity referred to as a hot spot phenomenon where spots are
generated about a center of pixels displayed on the display,
causing degradation of picture quality on the display. FIG. 4
illustrates in detail one of the causes generating the hot
spots.
[0014] If the size of a light emitting diode 10 is very small, an
amount of light emitted to a lateral surface of a lens by being
reflected from a surface 21 of a conical shaped groove according to
the prior art increases, but if the size of the light emitting
diode 10 is large, light (C) progressing at an angle less than a
critical angle from the surface 21 of the conical shaped groove
exists to allow the light to be emitted from an upper surface of
the lens, thereby generating the hot spot, because the surface 21
of the conical shaped groove totally reflects only the light (A)
progressing at an angle larger than the critical angle out of light
radiated from the light emitting diode 10.
[0015] At this time, light (B) progressing to a lateral surface of
the lens is nothing to do with hot spots, as shown in FIG. 4.
[0016] FIG. 5 illustrates a cross-sectional view of a light
emitting diode packaged in a printed circuit board according to the
prior art, where a plurality of lateral light emitting diode
packages 50 are packaged in a printed circuit board 60. As
mentioned, a printed circuit board packaged with lateral light
emitting diode packages is employed for a backlight unit as
depicted in FIG. 6.
[0017] FIG. 6 is a schematic cross-sectional view of a light
emitting diode employed for an LCD backlight unit according to the
prior art.
[0018] In order to address the problem of the light emitted to the
center of the light emitting diode package, an LCD backlight unit
is mounted with a hot spot baffle plate 80. In other words, an LCD
backlight unit 90 is configured in such a manner that hot spot
baffle plates 80 are mounted on each light emitting diode package
70 packaged in the printed circuit board 60, and a light guide
plate 85 is disposed on an upper surface of the hot spot baffle
plate 80, and an upper surface distanced from the light guide plate
85 is disposed with an LCD 95 to finish the assembly of the
backlight unit 90 and the LCD 95.
[0019] There is a disadvantage in the backlight unit 90 thus
constructed in that a plurality of light emitting diode packages 90
should be mounted thereon with hot spot baffle plates 80 called
diverters to complicate the assembly process.
[0020] There is another disadvantage in that if there is an
erroneous arrangement of the hot spot baffle plates 80 on the
plurality of light emitting diode packages 70, spots similar to the
hot spots are generated on a screen of a final display. Still
another disadvantage is that thickness of the display panel
increases as much as that of the hot spot baffle plate 80.
SUMMARY
[0021] In one general aspect, an optical lens comprises: a
reflection surface formed thereon for reflecting light emitted
upwards from thereunder; and a bottom refraction surface for
refracting the light emitted upwards from thereunder and allowing
the light to reach the reflection surface.
[0022] In another general aspect, a light emitting device package
comprises: a light emitting device for emitting light; and an
optical lens disposed with a reflection surface formed thereon for
reflecting light emitted upwards from the light emitting device and
a bottom refraction surface for refracting the light emitted
upwards from the light emitting device and allowing the light to
reach the reflection surface.
[0023] In still another general aspect, a backlight unit comprises:
a substrate; a plurality of light emitting devices packaged in the
substrate for emitting light; a plurality of optical lenses
disposed with a reflection surface formed thereon for reflecting
light emitted upwards from the plurality of light emitting devices
and a bottom refraction surface for refracting the light emitted
upwards from the plurality of light emitting devices and allowing
the light to reach the reflection surface; and a diffusion plate
disposed on the plurality of optical lenses.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a schematic view illustrating a light path from a
lateral optical lens according to the prior art,
[0025] FIG. 2 is a schematic perspective view of a light emitting
diode package of FIG. L.
[0026] FIG. 3 is a schematic view explaining one of the reasons why
a hot spot is generated from an optical lens according to the prior
art.
[0027] FIG. 4 is a cross-sectional view illustrating a printed
circuit board in which a light emitting diode is packaged according
to prior art.
[0028] FIG. 5 is a cross-sectional view illustrating a light
emitting diode packaged in a printed circuit board according to the
prior art.
[0029] FIG. 6 is a schematic cross-sectional view of a light
emitting diode employed for an LCD backlight unit according to the
prior art.
[0030] FIG. 7 is a cross-sectional view of an optical lens and a
light emitting device using the optical lens according to a first
embodiment of the present invention.
[0031] FIG. 8 is a schematic view of another function of the
optical lens according to the first embodiment of the present
invention.
[0032] FIGS. 9a to 9c are cross-sectional views of various shapes
of the optical lens according to the first embodiment of the
present invention.
[0033] FIG. 10 is a schematic cross-sectional view of a light
emitting diode package using an optical lens according to the first
embodiment of the present invention.
[0034] FIGS. 11a to 11d are light emitting distribution graphs of a
light emitting device package using an optical lens according to
the present invention.
[0035] FIG. 12 is a partial schematic cross-sectional view of an
optical lens according to the present invention.
[0036] FIG. 13 is a cross-sectional view of an optical lens and a
light emitting device using the optical lens according to a second
embodiment of the present invention.
[0037] FIG. 14 is a schematic view of a shape of a refraction
surface of an optical lens according to the second embodiment of
the present invention.
[0038] FIGS. 15a and 15b are cross-sectional views of an optical
lens in another shape according to the second embodiment of the
present invention.
[0039] FIGS. 16a and 16b are cross-sectional views of a light
emitting device bonded to a base member of a light emitting device
package according to the present invention.
[0040] FIG. 17 is a plan view of a plurality of light emitting
devices bonded to a base member of a light emitting device
according to the present invention.
[0041] FIG. 18 is a cross-sectional view of a substrate packaged by
light emitting devices using an optical lens according to the
present invention.
[0042] FIG. 19 is a cross-sectional view of a substrate packaged by
light emitting devices according to the present invention.
[0043] FIG. 20 is a schematic cross-sectional view of a backlight
unit according to the present invention.
DETAILED DESCRIPTION
[0044] Referring to FIG. 7, an optical lens 200 according to a
first embodiment of the present invention comprises: a reflection
surface 210 formed thereon for reflecting light emitted upwards
from a light emitting device; and a bottom refraction surface 220
for refracting the light emitted upwards from the light emitting
device and allowing the light to reach the reflection surface 210,
where a path of the light incident from thereunder is changed to
reach a lateral surface of the optical lens 200.
[0045] At this time, the optical lens 200 is comprised of a body.
The body is formed thereon with the reflection surface 210, and is
also formed with the bottom refraction surface 220 from which the
light incident thereunder is refracted and irradiated.
[0046] The light incident on the reflection surface 210 is the one
emitted from a bottom side of the body toward an upper side of the
body, and the light incident from the bottom side of the body is
composed of the one refracted and irradiated upward of the body and
the one irradiated to a lateral surface of the body. Preferably,
the optical lens 200 is further comprised of an external refraction
surface 230 formed at a lateral surface of the body for refracting
the light reflected from the reflection surface 210 and light
irradiated to the lateral surface of the body to be irradiated to
the lateral surface of the body.
[0047] In other words, the lateral surface of the body comprising
the optical lens is formed with the external refraction surface
230. Preferably, the bottom refraction surface 220 is formed at an
upper side of a light emitting device 100.
[0048] Preferably, the body of the optical lens 200 including the
reflection surface 210, the bottom refraction surface 220 and the
external refraction surface 230 is shaped of a hemisphere as shown
in FIG. 7. At this time, the reflection surface 210 is generated by
cutting the hemispherical upper side of the body to form an
intaglio-type look. Preferably, the external refraction surface 230
is a curved surface protruding outward for forming the hemisphere
except for a bottom portion of the hemisphere.
[0049] In the optical lens 200 thus configured according to the
first embodiment of the present invention, the light irradiated
upwards of the optical lens from the light emitting device 100 is
refracted from the bottom refraction surface 220 to reach the
reflection surface 210, where the reflection surface 210 reflects
the light. The external refraction surface 230 of the optical lens
200 refracts the light reflected from the reflection surface 210
and allows the light to be irradiated to the lateral surface of the
optical lens 200.
[0050] To be more specific, arrows `E1`, `E2` and `E3` of FIG. 7
respectively denote paths of the light emitted upwards of the light
emitting device 100, and the light is irradiated to the lateral
surface of the optical lens 200 by the bottom refraction surface
220, the reflection surface 210 and the external refraction surface
230.
[0051] Preferably, the reflection surfaces 210 are inclined, and
the bottom refraction surfaces 220 are symmetrically inclined from
the reflection surfaces 210 with respect to the horizontal line.
More preferably, the reflection surfaces are formed by removing an
upper side of the body in the shape of a cone, and the bottom
refraction surface is formed by removing a bottom side of the body
in the shape of a cone.
[0052] Meanwhile, the optical lens 200 is made of a material
selected from the group consisting of PC (Polycarbonate), PMMA
(Polymethylmethacrylate), silicon, fluorocarbon polymers, or PEI
(Polyetherimide).
[0053] As evidenced from the foregoing, a light emitting device
package using an optical lens according to the first embodiment of
the present invention comprises the optical lens composed of a
light emitting device 100 for emitting light, the bottom refraction
surface 220 for refracting the light irradiated upwards of the
light emitting device 100, the reflection surface 210 for receiving
the light refracted by the bottom refraction surface 220 and
irradiates the light to the lateral surface of the light emitting
device 100.
[0054] The optical lens optionally further includes the external
refraction surface 230 for refracting the light reflected from the
reflection surface 210 and the light irradiated toward the lateral
surface of the light emitting device 100 and emitting the light
towards the lateral surface of the light emitting device 100.
[0055] Now, referring to FIG. 8, the bottom refraction surface 220
of the optical lens serves to refract the light incident from the
light emitting device 100 in such a manner that the light can be
incident on the reflection surface 210 at an angle exceeding a
critical angle, if the reflection surface 210 formed at the optical
lens conducts a reflection operation by totally reflecting the
light incident at an angle (a) exceeding the critical angle.
[0056] In other words, the bottom refraction surface 220 at the
optical lens according to the present invention functions to
refract a path of the light irradiated upwards from the light
emitting device 100 so that the light can be incident on the
reflection surface at an angle exceeding the critical angle,
thereby reducing the amount of light irradiated upwards of the
optical lens to the maximum and simultaneously increasing the
amount of light irradiated to the lateral surface of the lens.
[0057] Consequently, there is an advantage in that generation of
hot spots occurring in the prior art can be limited to the maximum
if an optical lens and a light emitting device package employing
the lens are used for a backlight of a display.
[0058] Now, referring to FIGS. 9a to 9c, a reflection film 250 is
coated on the reflection surface 210 of the optical lens 200.
[0059] The reflection film 250 is formed with a metallic film or a
high reflective film, and the metallic film is made of any one of
Ag, Al or Rh, or a combination thereof. If the reflection film 250
is coated, the light is not emitted upwards of the lens 200 but is
emitted only through the lateral surface of the lens 200. In other
words, the hot spot occurring in the prior art is completely
removed to thereby enable to improve the picture quality of the
display.
[0060] Furthermore, as shown in FIG. 9b, if a non-permeable
material film 260a is further coated on an upper surface of the
coated reflection film 250, the light is prevented from permeating
through the reflection surface 210 of the lens 200 and exiting
upwards of the lens 200.
[0061] Concurrently, as illustrated in FIG. 9c, the V-shaped
grooved reflection surfaces 210 may be coated with the reflection
film 250 and be filled with non-permeable material film 260b.
[0062] FIG. 10 illustrates an example of a light emitting device
package, where the light emitting device 100 is bonded to a hit
slug 301 of a base member, and is bonded by wires 311 to leads 310a
and 310b which are terminals each disposed at an external side
distanced from the hit slug 301, where the light emitting device
100 and the leads 310a and 310b are electrically connected.
Furthermore, part of the light emitting device 100, the hit slug
301 and leads 310a and 310b are wrapped by a molding unit 320.
[0063] At this time, part of the heat slug 301 is exposed outside
of the molding unit 320 to allow heat generated from the light
emitting device 100 to be easily discharged, and the leads 310a and
310b are exposed outside of the molding unit 320 to be electrically
connected to the outside. The optical lens 200 is bonded to an
upper side of the molding unit 320 by way of an adhesive 350.
[0064] Although the light emitting device may be bonded to a base
member such as the heat slug 301 or the like as depicted in FIG.
10, the light emitting device is flip-chip bonded to conductive
lines if a sub-mount substrate formed with the conductive lines is
a base member, or if the base member is a substrate formed with a
reflection-groove, the light emitting device is bonded to the
reflection-groove of the sub-mount substrate. Accordingly, methods
vary for implementing a structure of a light emitting device
package using the optical lens 200.
[0065] FIGS. 11a to 11d are light emitting distribution graphs of a
light emitting device package using an optical lens according to
the present invention.
[0066] Referring to FIG. 12, an inclination (.alpha.1) of the
reflection surface 210 at the optical lens 200 may be adjusted in
consideration of the lateral light emitting characteristic. The
inclination (.alpha.1) is an angle formed between the reflection
surface 210 and a perpendicular line (O) extended from an apex of
the v-shaped groove. A light emitting distribution with respect to
the inclination (.alpha.1) is such that a light output is 100% at
45 degrees of the inclination (FIG. 11a), 98% at 55 degrees (FIG.
11b), 93% at 65 degrees (FIG. 11c) and 81% at 75 degrees (FIG.
11d).
[0067] However, as noted from the light emitting distribution
graphs, as the inclination goes from 45 degrees to 75 degrees, the
light is further emitted to the lateral surface of the lens.
[0068] After all, a lateral surface light emitting distribution and
a light emitting efficiency are correlated with respect to the
inclination, such that it is preferable that the inclination be in
between 20 degrees and 80 degrees in order to maintain an optimum
light distribution.
[0069] Now, referring to FIG. 13, an optical lens according to a
second embodiment of the present invention is formed with a
marginal refraction surface 221 for refracting the light in
addition to the bottom refraction surface 220 of the first
embodiment of the present invention of FIG. 7, so that light
emitted from an upper margin of the light emitting device 100 can
have a path on which the light is reflected from the reflection
surface 210.
[0070] Furthermore, the marginal refraction surface 221 may be a
symmetrically inclined surface formed by a perpendicular line (E)
and the inclined bottom refraction surface 220.
[0071] To be more specific on the structure of the optical lens,
the lens is disposed thereon with a V-shaped conical groove, where
surfaces of the conical groove are used for reflection surfaces,
and the lens is also formed thereunder with a cylindrical groove by
removing a bottom thereof in which a light emitting device 100 is
mounted as shown in FIG. 13. The cylindrical groove is formed
thereon with a W-shaped (sawtooth) intaglio.
[0072] Consequently, if the optical lens according to the second
embodiment of the present invention is employed for a large-sized
light source, the light irradiated from the margin of the light
emitting device is refracted by the bottom refraction surface 220
to prevent the light from deviating from a light path reflected
from the reflection surface. The marginal refraction surface 221
serves to refract the light irradiated from the margin of the light
emitting device to a path for reflecting the light from the
reflection surface and to emit the light to lateral surfaces (F1
and F2 paths) of the lens.
[0073] The configuration of the optical lens may be freely designed
and changed by using a refraction path of light (Light is reflected
back into a denser medium if the angle of incidence is less than a
certain critical angle when the light travels from the denser
medium into a less dense medium and vice versa.) generated by a
difference of refractive index between a light emitting device and
air into which the light is emitted.
[0074] Furthermore, the optical lens is composed of a body
symmetrized by a central axis, where the body includes reflection
surfaces and marginal refraction surfaces.
[0075] If the refraction surface is inclined toward the central
axis, it is preferable that the marginal refraction surface be also
inclined toward the central axis. The object of the present
invention may be realized by an optical lens employing a single
constituent element of a marginal refraction surface, by allowing
the marginal refraction surface to perform a function of refracting
light irradiated from upward of a light emitting device and of
bringing the light to a reflection surface.
[0076] Meanwhile, width (W1) of the bottom refraction surface 220
in FIG. 13 may be so designed as to be wider than that (W2) of a
light emitting device. Furthermore, the optical lens according to
the second embodiment of the present invention is the same as that
of the first embodiment except that there is an additional marginal
refraction surface on the optical lens.
[0077] Now, referring to FIG. 14, a bottom refraction surface and a
marginal refraction surface may be respectively concaved. These
types of concaves can also refract light irradiated upward of a
light emitting device to allow reaching the reflection surface 210
and enable to reflect the light toward the lateral surfaces of the
lens from the reflection surface 210.
[0078] Now, referring to FIG. 15a, a convex external refraction
surface 230 is externally formed at the optical lens and is formed
thereunder with a locking hole 231 for easing and expediting the
assembly of the lens. Referring to FIG. 15b, a convex external
refraction surface 230 may be formed by combining a convex surface
230a and a plain surface 230b.
[0079] As described erstwhile, the present invention can increase
an amount of light irradiated toward the lateral surface of the
lens in comparison with the prior art.
[0080] Now, referring to FIG. 16a, a base member 380 may be bonded
by devices comprising: a blue light emitting device 101a for
emitting blue light; and a yellow light emitting device 101b for
emitting yellow light to enable to emit white light to a lateral
surface. As depicted in FIG. 16b, the base member 380 may be bonded
by devices comprising: a red light emitting device 102a for
emitting red light; a green light emitting device 102b for emitting
green light; and a blue light emitting device 102c for emitting
blue light to enable to emit the white light to a lateral
surface.
[0081] Meanwhile, although it is not shown in the drawing, a single
light emitting device for emitting white light may be bonded to the
base member 380 to allow the white light to be emitted to the
lateral surface.
[0082] FIG. 17 is a plan view of a plurality of light emitting
devices bonded to a base member of a light emitting device
according to the present invention, where dotted lines refer to an
area where an optical lens is mounted, and a base member of a light
emitting device is disposed in the area where the lens is
mounted.
[0083] The base member 380 is bonded thereon by a plurality of
light emitting devices 103, enabling to improve a light output. The
plurality of light emitting devices 103 are composed of any of the
white light emitting devices, red/blue/green light emitting
devices, and blue, yellow light emitting devices.
[0084] Now, referring to FIG. 18, an upper surface of a substrate
400 is mounted by a plurality of light emitting devices 100, each
device 100 spaced a predetermined distance apart, by way of
conductive bonding method, where each light emitting device 100 is
wrapped by the optical lens 200 of the present invention.
[0085] If the light emitting device 100 is directly bonded to the
substrate 400, thickness of a display panel can be decreased when
the light emitting device is used for a backlight unit.
[0086] FIG. 19 is a cross-sectional view of a substrate packaged by
light emitting devices according to the present invention, where a
plurality of light emitting device packages mounted with optical
lenses 530 are packaged on an upper surface of the substrate 400,
each package being spaced a predetermined distance apart.
[0087] The substrate 400 packaged by the plurality of light
emitting device packages 530 may be employed for a backlight unit
of a display. However, unlike the prior art, there is no need of
using a hot spot baffle plate called a diverter, such that an
assembly work of the display panel can be simplified and an
erroneous array of the hot spot baffle plate can be prevented.
There is another advantage in that lateral light emission
efficiency is excellent to enable to improve the picture quality of
the display. There is still another advantage in that the thickness
of the display panel can be reduced as much as that of the hot spot
baffle plate to enable to decrease the thickness of the overall
thickness of the display panel.
[0088] The aforementioned optical lens and a light emitting device
package using the optical lens may be applied to all industrial
devices including displays, illumination devices, electric bulletin
boards and switches for automobiles, and are not limited to the
fields thus mentioned.
[0089] FIG. 20 is a schematic cross-sectional view of a backlight
unit according to the present invention, where the backlight unit
using an optical lens according to the present invention comprises:
a substrate 400; a plurality of light emitting devices 100 packaged
on the substrate 400 for emitting light; a plurality of optical
lenses 200 including a reflection surface formed thereon for
reflecting light emitted upwards from thereunder, and a bottom
refraction surface for refracting the light emitted upwards from
thereunder and allowing the light to reach the reflection surface;
and a diffusion plate 500 disposed on the plurality of optical
lenses 200.
[0090] The backlight unit of FIG. 20 uses the substrate of FIG. 18,
and if the substrate of FIG. 19 is employed, the backlight unit may
be further disposed with a base member on which the light emitting
devices are bonded, terminals electrically connected to the light
emitting devices, and a molding unit for partially exposing the
terminals and wrapping the light emitting devices and the base
member. In other words, the light emitting devices are packaged by
the molding unit and the optical lens is attached to an upper
surface of the molding unit.
[0091] Meanwhile, the diffusion plate 500 is mounted thereon with a
liquid crystal display panel 600.
[0092] As apparent from the foregoing, there are advantages in the
present invention thus described according to the present invention
in that light irradiated upward of a light emitting device is
refracted from a bottom refraction surface to allow reaching a
reflection surface, and an optical lens is mounted for reflecting
the light sideways of the lens from the reflection surface to
minimize an amount of light irradiated upward of the lens while
increasing the amount of light irradiated toward the lateral
surface of the lens, thereby limiting the generation of a hot spot
to the maximum.
[0093] There is another advantage in that the present invention
dispenses with a hot spot baffle plate and a complicated assembly
process to enable to reduce the number of parts and to decrease the
thickness of a panel.
[0094] Although various embodiments utilizing the principles of the
present invention have been shown and described in detail herein,
and various preferred modes of operation are provided, those
skilled in the art can readily devise many other variances,
modifications, and extensions that still incorporate the principles
disclosed in the present invention. The scope of the present
invention embraces all such variances, and shall not be construed
as limited by the number of active elements, wiring options of
such, or the polarity of a light emitting device therein.
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